Land Telemetry - Overview

Land emits telemetry through two parallel pipes that share one trace_id:

Pipe	Sink	Strength	Cost
PostHog	`https://eu.i.posthog.com`	Aggregations, dashboards, retention	One event per millisecond cap
OTLP	`127.0.0.1:4318` (Jaeger)	Per-request waterfall, parent/child	Local-only, requires collector

Joining the pipes: every PostHog event carries $trace_id and $span_id properties; every Jaeger span carries posthog.event / posthog.distinct_id attributes. A HogQL JOIN against Jaeger’s trace export - or a manual click-through from a PostHog event into the Jaeger UI - reconstructs the full causal chain.

Layout

Layer	File / Module	Pipe(s)
Build.sh	`Maintain/Script/PostHogCapture.sh`	PostHog + OTLP
Mountain	`Element/Mountain/Source/Binary/Build/PostHogPlugin/*`	PostHog
Mountain	`Element/Mountain/Source/IPC/DevLog/EmitOTLPSpan.rs`	OTLP
Mountain	`Element/Mountain/Source/Telemetry/*`	OTLP (tracing)
Cocoon	`Element/Cocoon/Source/Telemetry/PostHogBridge.ts`	PostHog
Cocoon	`Element/Cocoon/Source/Telemetry/OTLPBridge.ts`	OTLP
Wind	`Element/Wind/Source/Telemetry/Bridge.ts`	both
Sky	`Element/Sky/Source/Function/Telemetry/Bridge.ts`	both
Output	`Element/Output/Source/Telemetry/*`	both
Sidecars	re-export Mountain’s macros via the `tracing` crate	OTLP

Event-name convention

Every Land-emitted event uses the prefix land:<element>:<action>:

land:build:start, land:build:phase:complete, land:build:complete, land:build:error
land:mountain:session:start, land:mountain:ipc:invoke, land:mountain:handler:complete, land:mountain:error
land:cocoon:session:start, land:cocoon:entry:load, land:cocoon:entry:loaded, land:cocoon:handler:complete, land:cocoon:stub:active, land:cocoon:error
land:wind:layer:ready, land:wind:command:invoke
land:sky:build:complete, land:sky:resource:error, land:sky:throttle-dropped
land:output:build:complete
land:session:start, land:session:end - Sky-emitted aggregates
land:boot:timing - workbench boot percentile telemetry
land:ipc:marks, land:vscode:marks, land:extension-host:marks, land:all:marks - performance mark batches

PostHog’s $exception autocapture stays as-is; treat it like a PostHog-special name.

Configuration - `.env.Land.PostHog`

Single source of truth for both pipes. Read at boot by every layer.

Var	Default	Effect
`Authorize`	`phc_…`	PostHog project key
`Beam`	`https://eu.i.posthog.com`	PostHog endpoint
`Report`	`true`	Master toggle for the PostHog pipe
`OTLPEndpoint`	`http://127.0.0.1:4318`	OTLP collector
`OTLPEnabled`	`true`	Master toggle for the OTLP pipe
`Capture`	`true`	Master telemetry kill - short-circuits both
`Trace`	`all`	RUST_LOG-like span filter
`Record`	`0`	Mirror every payload to a per-session NDJSON
`Brand`	(empty - per-process)	`distinct_id` seed
`Throttle`	`5`	posthog-js client-side rate-limit
`Buffer`	`3000`	Cocoon batch window (ms)
`Batch`	`20`	Cocoon batch size
`Cap`	`7`	Sky `$exception`/10 s
`Replay`	`false`	posthog-js session recording
`Ask`	`false`	posthog-js surveys

Production = zero bytes

Every layer compiles the telemetry stack out of release builds:

Rust (Mountain, Air, Echo, Rest, Grove, Mist) - capture paths gate on cfg!(debug_assertions). LLVM dead-codes them in --release.
TypeScript - bridges import lazily through if (process.env.NODE_ENV !== "production") { … } so esbuild’s define collapses the conditional and tree-shakes the SDK.
Astro - bundle config check if (import.meta.env.DEV) drops the posthog-js + OTLP SDK paths from astro build.

Plus the runtime kill switches: Capture=false short-circuits all pipes regardless of build mode; Report=false / OTLPEnabled=false flip a single pipe. (Capture is the telemetry switch; the unrelated Disable in .env.Land.Diagnostics controls polyfill / shim loading.)

Bring-up sequence

# Once - bring up the local Jaeger collector.
sh Land/Container/Up.sh

# Every dev session - env vars feed every layer.
export Trace=all Record=1 Capture=true
sh Land/Maintain/Debug/Build.sh --profile debug-electron-bundled

# Run the binary; Mountain initialises both pipes from `.env.Land.PostHog`.
export Trace=all
./Element/Mountain/Target/debug/<binary>

# Inspect:
#   PostHog dashboards: https://eu.posthog.com/project/151871
#   Jaeger UI:          http://127.0.0.1:16686

See Effect-OTel.md for the Effect-TS integration pattern Wind / Cocoon use, and Tree-Shaking.md for the production-zero contract.